Fluid actuated sawmill dogging mechanism



y 19. B. w. TAUBE 2, 0

FLUID ACTUATED SAWMILL DOGGING MECHANISM Filed Dec. 9, 1949 3 Sheets-Sheet 2 II[IIIIIIIIIZ INVENTOR.

ATTOR/Vf) July 29, 1952 B. w, TAUBE- FLUID ACTUATED SAWMILL DOGGING MECHANiSM 3 Sheets-Sheet 3 Filed Dec. 9, 1949 INVENTOR. je zmzil, Team WMWM Patented July 29, 1952 FLUID ACTUATED SAWMILL DOGGIN G MECHANISM Bernhard W. Taube, Milwaukee, Wis., assignor to The Filer & Stowell 00., Milwaukee, Wis, a corporation of Wisconsin Application December 9, 1949, Serial No. 132,099

4 Claims. (Cl. 143-125) 1 This invention relates to improvements in sawmill carriages and particularly to board dog movement cylinders and the control thereof.

Heretofore the dogs have been changed from 2 trol of board-dogging and board-aiming is accomplished by the continuous depressing of a foot pedal which rotates the master control valve, such a foot pedal being presently used to control log-dogging position to board-dogging position 5 only the dogging action. by means of a two position cylinder. However, The novel features, which are considered charwhen the dogs were in the board-dogging posiacteristic of the invention, are set forth with tion it was impossible to thereafter adjust such particularity in the appended claims. The inposition. Consequently, if the board was not vention itself, however, both as to its organizafiush ainst the knee after being dogged, or if tion and its method of operation, together with there was some lost motion due to wear on the additional objects and advantages thereof, will parts, an imperfect board would be cut. best be understood from the following descrip- It is an object of this invention, therefore, to tion of a specific embodiment when read in conprovide a board dog movement cylinder which nection with the accompanying drawings, in in addition to controlling the selective positions which: of the dogs also moves the dogs after a board Fig. 1 is a fragmentary view in side elevation has been dogged to bring such board or backing with parts being shown in section for sake of board tightly against the knee and thereby clarity in illustration of the knee of a saw mill eliminate any lost motion or clearance and thus carriage including a board dog movement cylininsure the accurate positioning of the log or 0 der embodying the present invention, the dogs board prior to'sawing. being shown in logedogging position with the It is a further object of this invention to promaster piston of the cylinder at its outer end; vide a board dog movement cylinder which is Fig. 2 is a view partly in elevation and partly automatically operated after the dogging o-perain section of suchboard-dogging cylinder with tion to move the board as dogged into tight enthe master piston shown in the intermediate ,pogagemen-t with the knee by the same control used sition and the dogs in board-dogging position; for the dogging operation. Fig. 3 is a view similar to that of Fig. 2 with These objects are obtained by providing a dual .the master piston and secondary piston in the acting board dog movement cylinder having a inner position and thedogs in board or back master piston which is movable to the outer end board clamping position; of the cylinder to place the dogs-in log-dogging Fig. 4 is a diagrammatic view of the control position and movable to an intermediate posisystem for such board dog movement cylinder tion against a secondary piston to retract the and the control valve for the dogging operation dogs to board doggin-g position. Such movements embodying the present invention, the master conare controlled by a manually operated selector 35, trol rotary valve being viewed in end elevation valve. The secondary piston moves within the with its cover removed to illustrate the normal cylinder between the intermediate position and or first position of the rotary member; f an inner position, sliding freely on the piston Fig. 5 is a view of the master control rotary rod. It is normally urged to intermediat povalve similar to that of Fig. 4' with the rotary sition when a -master control rotary valve is member in dogging control or second position; placed in the'position'to cause'the dogging cyl- Fig. 6 is a view of the master control rotary 'inder to operate.- -However, when such master valve similar to that of Fig. 4 with the rotary control valve is movedbeyond such position the member in board clamping control or third ,posecondary piston will move to the inner end of sition; and a v the board dog movement cylinder thereby allow Fig. 7 (Sheet 2) is a view in top elevation of ing the master piston to move the dogs inwardly the master control rotary valve and f ot pedal while they are dogging aboard to clamp such for operating thesame. j I t Y board against the knee and take up any lost mo- Referring to the drawings by reference nution in'th'e dogging mechanism. Thus the board merals, the knee i0 is mounted on a saw mill or backing board is properly alined and the carriage in the usual manner and has assoproper cutting of the lumber insured. With this ciated therewith an upper .dog holder l2 and type of board dog movement cylinder and condog bar I l. The upper dog holder l2 ridesup trol the operator automatically performs the and down on the dog bar 14 under, control of a board alining and tightening without any condogging cylinder l5 mounted atthe lower end scious additional manipulation, {The entire conofthedog bar .witli thelower'dog H. ,The piston rod (9 of the dogging cylinder is fastened to the upper dog holder l2. Th dog bar i4 is suspended by two shafts l6 pivoted to upper and lower bell cranks l8 pivotally mounted in bearings 28 secured to the knee. The bell cranks are interconnected-by a rod 22 and move in unison. An extension 24 on the upper bell crank is secured to the piston rod 26 and both cranks are oscillated thereby. In Fig. l the full lines show the bell cranks in the first position and the dogs 28 in the fully extended or log-dogging position. The bell cranks are rotated counter-clockwise to the second position shown in broken lines to move the dog bar l4 inwardly of the knee and bring the dogs 28 into board-dogging position shown in the broken lines. As thus described, the mechanism is substantially the same as that shown in the patents to F. E. Martin Nos. 1,840,846 and 1,930,014, and as is well known in this art the dogs are selectively positioned in either extended log-dogging position or retracted board-dogging position through the medium of a two-position cylinder. The upper dogs 28 are moved downwardly with respect to a lower dog (not shown) to accomplish the dogging action after the selection of'the dog position. Such dogging action is ultimately controlled by a master control rotary valve. However, after a board or backing board has been dogged it is often not held closely against the face of the knee and as a result imperfect boards are sawed therefrom. Therefore, in this improvement the bell cranks l8 are swingable toward, and in some cases the entire distance to, the third position shown in broken lines in Fig. 1. This movement causes the dogs 28 to be drawn inwardly toward the face of the knee for a total distance of approximately a quarter of an inch. This inward movement, which takes place after a board has been dogged takes up slack in the mechanism and clamps the board or backing board flush against the face of the knee, thus correctly alining it. This third position is herein referred to as clamping position.

The movement of the bell cranks from the logdogging position to board-dogging position, and, after dogging a board, toward the clamping position, is controlled by a dual piston boarddogging movement cylinder 38. This cylinder is pivotally mounted at 32 to the knee [8 in the customary manner. It has a small diameter long bore 34 and a large diameter short bore 36. A master piston 38, operable in the bore 34, is fixedly secured to the end of the piston rod 26, to efiectuate the movement thereof. A secondary piston 40, operable in the bore 36, is slidable along the piston rod 26. The piston rod 26 enters the cylinder through the customary packing gland 42 and its outer end is connected with the extension 24 to operate the bell cranks. The ports to the bore 34 are of known design and have two branches 44 and 45 leading to such bore. The branches 4B are located inwardly from the extreme ends of the normal travel of the master piston and are covered thereby before it reaches such ends. A ball check valve 48 between such branches permits pressure to be applied to each branch 44 when the piston is in such extreme ends. However, after the piston closes the branches 46 a back pressure is developed in, branches 44 which cushions the stopping of thepiston. It has been found, however, that as the piston 38 is stopped in the board-dogging position of Fig. 2 such back pressure will tend to move the secondary piston 49 from its normal position and the piston 38 will not stop in the same place. To avoid this a small by-pass hole 50 extends between the branches 44 and 46 at the inner end of bore 34. This restricted opening is suificiently small to cause back pressure to develop but after the piston 38 is stopped it will permit escape of pressure and let both pistons come to rest in the exact position. The bore 36 has only one port 52 by which pressure is applied to the upper side of the secondary piston 48 to cause it to stop the master piston 38 at the extreme end of its normal travel shown in Fig. 2.

The operation of the dual acting cylinder 38 is controlledby a system diagrammatically shown in Fig. 4 which includes a source of fluid pressure, a manual selector valve 54, and a master rotary valve 10. The two position manually operated selector valve 54 is connected to the source of fluid pressure (not shown) by a conduit 56, to the port at the lower end of bore 34 by a conduit 58, and to the port at the upper end of bore 34 by conduit 60. This valve also has an atmospheric exhaust 62. When valve lever 64 is in the position shown, the source of fluid pressure is connected to the upper port of the bore 34 and the lower port is connected to the exhaust 62. This moves the piston 38 to and maintains it in the normal position of Fig. 1 with the dogs 28 in log-dogging position. When the valve lever 64 is placed in its second position (not shown) the source of fluid pressure is connected with the lower port of bore 34 and the upper port is connected to the exhaust 62. This moves the piston 38 to the position shown in Fig. 2 where it is stopped by the secondary piston 48 and the dogs 28 are in board-dogging position. The operator can thus manually select either the log-dogging position of Fig. 1 or the board-dogging position of Fig. 2 before dogging a logor board. Assuming that the piston is moved to the log-dogging position shown in Fig. 1, and the log is then dogged in the customary manner, the operator may clamp the log so dogged against the knee [0 by moving the selector valve 54 to the boarddogging position. This would-tend to move pieton 38 upwardly and thereby take up any slack in the mechanism and bring the log closely against the knee.

The dogging operation for either logs or boards is accomplished by the dogging cylinder l5. The fluid pressure for dogging enters through the conduit 65 to the automatic manifold valve 66 and thence through conduit 68 to the top of such dogging cylinder. A hose stand valve diagrammatically shown at 61 (Fig. 1) is normally open to permit fluid pressure to enter at 69 and raise the upper dogs 28. It is closed whenever the automatic manifold valve 66 is opened to cut off such pressure from the lower end of cylinder I 5. This is standard mechanism well known to those skilled in this art and is therefore not described in detail. The automatic manifold valve 66 is held in closed position by fluid pressure from a master control v valve 18 connected thereto by conduit 12. When the master control valve 16 cuts off fluid pressure to conduit 12 the dogs 28 are automatically dogged. The master control valve 10 is also connected by a conduit 14 to the port 52 and supplies fluid under pressure to such port to normally hold the secondary piston 48 in the position of Figs. 1 and 2. The master control valve 18 has acylindrical body 16 provided with a mounting bracket 18by which the valve may be secured to a desired place on a saw mill carriage. A rotary member 80' is mounted in the body E5 and has a shaft 82 projecting from .the end of such body so that such member may be rotated thereby. The rotary member 80 has two diametrically positioned ports 84 and 85 out therethrough as shown so as to'provide communication between the front face of the member and the portsin the body It. The rear face of the member 80 is provided with circumferentially extending recesses 88 and 9 These recesses provide communication between the ports in the body 16 in the positions of the rotary member 80 shown in Figs. 5 and 6. The body It has four ports 92, 94, 96, and 98 which are angularly spaced as shown and communicate respectively with the conduits l2, IOU, I l, and E02. The source of fluid pressure is connected by the pipe 194 to the cover H36 (see Fig. 7) When the cover is placed'on the body 16, as shown in Fig. 7, the fluid pressure is directed to the front face of the rotary member 89, as indicated by the arrow and designation in Fig. 4. A foot pedal I08 is fastened in suitable manner to the shaft 82, and when moved in a counter-clockwise direction, as viewed in Fig. 4, the rotary member 863 will be continuously moved from the normal position shown in Fig. 4, through the dogging position shown in Fig. 5, to the clamping position shown in Fig. 6.

When the rotary member 80 is in the normal position shown in Fig. 4, fluid pressure passes through port 86, port 96, and conduit M, to the upper end of bore 36, to normally continuously hold the secondary piston 40 in the position shown in Figs. 1 and 2 so that it provides a block for the master piston 38 limiting the latters movement between the extreme end positions shown in such figures. Thus the dog board movement cylinder is under the control of the manually operated selector valve 54 and may move the dogs 28 between board-dogging position and log-dogging position. In this normal position of the rotary valve the fluid pressure also passes through port 84, port 92, and conduit 12, to the operating plunger of the automatic manifold valve 66 to keep that valve in closed position. When the operator moves the foot pedal I98 counter-clockwise so that the rotary member 89 is moved to the dogging position shown in Fig. 5, fluid pressure will still be admitted to the upper end of bore 36 in the manner described above. However, fluid pressure will be disconnected from the operating plunger of valve 66 and instead such operating plunger will be exhausted to atmosphere through the conduit 12, port 92, recess 90, port 93, and the conduit [92. The automatic manifold valve 68 will then open and permit fluid pressure to pass through the conduits 64 and 68 to the dogging cylinder to actuate the dogs 28 in the well-known manner. As the foot pedal Hi8 continues its counterclockwise motion, the rotating member 80 will then be moved into the clamping position shown in Fig. 6. In this position the upper end of the bore 38 is disconnected from the source of fluid pressure and exhausted to atmosphere through conduit Hi, port 96, recess 88, port 94, and conduit H30. As the recess 50 is longer than the recess 88 such additional movement of the member will not disturb the connections to the operating plunger of the manifold valve 65 and it will still be exhausted to atmosphere in the manner described above and the dogs will remain dogged. The disconnection of fluid pressure from the upper end of the bore 36 permits the tirely upon the space between the sawed-off face of the board or backing board and the face of the knee. It has been found that a maximum permissible withdrawal of a .quarter of an inch is suflicient to take up any play in the parts and to bring such board. or backing board flush against the face of the knee to properly aline it. As the foot pedal l 08 is moved clockwise back to its normal position the dogs will be unclamped and .undo'gged and moved to the position selected by the manually operated selector valve54 where they will be ready for repetition of the operaion.

On important feature of this control is that it requires no thought or conscious effort on the part of the operator. The operator merely moves the foot pedal I08 in the manner in which it has been previously utilized to effect dogging operation. However, during such movement the control valve moves through the dogging position to the clamping position, and effects the clamping action automatically and as part of the dogging operation.

Although only one embodiment of the invention is shown and described herein, it will be understood that this application is intended to cover such changes or modifications as come within the spirit of the invention or scope of the following claims.

I claim:

1. In a saw mill carriage having knees and dogs movable with respect to said knees to retracted position, fully extended log-dogging position, or intermediate partially extended boarddogging position, a first fluid pressure means for moving said dogs to either of said positions, a secondary control valve for causing said first means to move said dogs to either log-dogging position or board-dogging position, a second fluid pressure means for dogging said dogs, and a master control valve for causing said second means to dog said dogs and said first means to move said dogs toward retracted position.

2. A saw mill carriage as claimed in claim 1 in which said first fluid pressure means consists of a pivoted cylinder having a piston rod operatively connected with said dogs for movement thereof, a master piston secured to said rod, and a secondary piston slidably mounted on said rod and operable to cause said master piston to stop in an intermediate position to place said dogs in said board-dogging position, said master control valve acting to release said secondary piston and let said master piston move toward a retracted position to move said dogs toward said retracted position.

3. In a saw mill carriage having knees and dogs movable with respect to said knees to retracted position, fully extended log-dogging position, or intermediate partially extended boarddogging position, a fluid pressure cylinder carried by said carriage and having a piston rod operatively connected with said dogs, said cylinder having a small diameter elongated bore and a larger diameter shorter bore, a master piston connected with said rod and slidable in said small bore, a secondary piston loosely slidable on said rod and slidable in said larger bore to a position limiting the movement of said master piston, a source of fluid pressure, a first control valve for admitting pressure to either side of said master piston to control the position thereof to cause said dogs to be moved to log-dogging position or board-dogging position, and a second control valve having a first position for dogging said dogs and a second position for controlling fluid pressure from said source to the outer side of said secondary piston to allow said secondary piston to cease limiting the movement of said master piston and thereby cause said dogs to move toward retracted position and thereby properly clamp a board against the knee.

4. In a saw mill carriage having knees and dogs movable with respect to said knees to retracted position, fully extended log-dogging position, or intermediate partially extended boarddogging position, a first fluid pressure means for moving said dogs to either of said positions, a control valve for causing said first means to move BERNHARD W. TAUBE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,561,341 Martin Nov. 10, 1925 1,590,105 Martin June 22, 1926 1,840,846 Martin Jan. 12, 1932 1,930,014 Martin Oct. 10, 1933 2,397,106 Haller Mar. 26, 1946 

